Intrauterine drug delivery is becoming increasingly important in gynecological practice. Intrauterine drug delivery can be used for contraception and treatment of various gynecological conditions. However, with existing intrauterine systems, delivering hormones in the uterus, there are several drawbacks which can be improved such as the ease of insertion in the uterine cavity, adaptation of the plastic frame to different sizes and shapes of uterine cavities to minimize side effects, retention of the IUD in the uterus, retrieval of the intrauterine foreign body from the uterus and visibility of the body on ultrasound examination.
The plastic frame of intrauterine devices (IUD) often creates dimensional incompatibility with the uterine cavity which could give rise to complaints such as abnormal uterine bleeding and cramping pain. Incompatibility also leads to displacement and expulsion of the IUD.
In an attempt to improve compatibility with uterine cavities of different sizes and shapes, and avoid expulsion and translocation, the “Multiload®” IUD (Organon) was created wherein the arms are approximately in the shape of the letter “omega” (see U.S. Pat. No. 3,952,734) and comprise lateral extensions. However, although the curved arms can adapt to the width of various uterine cavities, the arms are not enough resilient and, therefore, downward displacement of the IUD is not prevented by the design characteristics of the IUD. The arms of the Multiload® IUD also form an integral part of the plastic frame and cannot rotate during retrieval of the device from the uterine cavity. Removal of the Multiload IUD® requested by the woman is therefore sometimes difficult, painful and could also damage the uterus. One or both arms could also break off during removal of the device which can lead to complications.
Ultrasound examination has become routine in gynecological practice. The proper performance of the IUD is related to the proper position of the IUD in the uterine cavity. The assessment of the proper location of an intrauterine system in the uterine cavity by ultrasound which does not contain a metal such as copper is sometimes difficult, especially if there are uterine abnormalities.
To enhance the visibility of the drug-releasing IUD on ultrasound, the development of simple means will facilitate the location of the device in the uterine cavity. This can be accomplished by increasing the density of a part of the drug delivery compartment. The best way to assess the proper location of the IUD in the uterine cavity is by measuring the distance between the outer and upper surface of the uterus and the upper extremity of the drug delivery compartment. The more denser part of the drug delivery rod should therefore be selected to make it denser and more visible on ultrasound.
Another important aspect is the assembly of the plastic frame with the drug delivery compartment. The assembly of a plastic component which has multiple curves, with the rod-shaped drug delivery compartment is not evident. First, from a manufacturing point of view it is important that the plastic part can easily be assembled with the drug delivery rod. Therefore, the plastic frame should be resilient to allow straightening of the curves. The frame should not be provided with hooks or prongs such as those provided in the Multiload® IUD which would prevent the assembly with the drug delivery compartment. Secondly, it should be so constructed that its acts as a proper retaining member and, simultaneously, allows adaptation to the great differences in width of uterine cavities and thirdly, the assembly should allow easy upward rotation of the plastic frame during caudal traction on the IUD to allow easy removal of the IUD from the uterine cavity.
The aim of the present invention is to optimize intrauterine drug delivery to facilitate insertion, enhance acceptability and tolerance, improve retention, facilitate or even make removal possible and enhance visibility by ultrasound to allow assessment of the proper positioning of the IUD in the uterine cavity. To this end, the present invention concerns the design of a new platform for the delivery of drug(s) in the uterus for contraceptive and treatment purposes, easy to insert and remarkable well tolerated by parous, nulligravid/nulliparous women and women in the postmenopausal phase which have uteri which markedly differ in size and shape and are usually very small.
The present invention constitutes also an improvement of the intrauterine device disclosed in WO 03/068117 or U.S. Pat. No. 7,080,647 B2, these latter documents being incorporated herein by reference.